Rotatable shafts are commonly braked or held against rotation by a disk brake which includes a disk and an mechanism for applying a brake member against the disk. A variety of brake mechanisms have been utilized, such as wedges or balls that act as cams to advance a braking member against the brake disk. However, these prior art devices utilized relatively complex parts such as shafts slideable in cylindrical slider bearings to operate calibers for engaging opposite sides of a brake disk. The design of such brakes not only entails the production of a variety of different types of parts, but also results in a relatively bulky brake mechanism. A brake mechanism of relatively simple design which utilized a minimum number of moving parts, with the moving and stationary parts of a simple design that facilitated production and with the mechanism being compact, would have considerable utility.